What is the ideal gear motor protection?

The ideal vertical gear reducer protection is not the most functional, nor the so-called the most advanced, but should be the most practical. So what is it practical? Practical should meet the reliable, economical, convenient and other factors, with a high cost performance. So what is it? Reliable first should meet the function of reliable, such as the use of motor when the motor over-current, phase failure function must be on a variety of occasions, a variety of processes, various ways of over-current, phase can be reliable action. Followed by its own reliable (since the protector is to protect others, in particular, should have a high reliability) must have a variety of harsh environment of adaptive stability, durability.
Economy: the use of advanced design, reasonable structure, specialization, large-scale production, PC gearboxes product costs, to the user to bring high economic benefits.
Convenience: must be installed, used, adjusted, wiring, etc., at least should be similar to thermal relays, as much as possible easier and convenient.
It is also because of this, the experts have long predicted that in order to simplify the variable ratio gearbox protection device should be designed and used without power transformer (passive) design, and the use of semiconductors (such as SCR) instead of contact electromagnetic operating units. In this way, it is possible to manufacture a gearbox protection device consisting of a minimum number of components.